What Does "episcopal"

“Episcopos” is the Greek word for “bishop.” Thus “Episcopal” means “governed by bishops.” The Episcopal Church maintains the three-fold order of ministry as handed down by the Apostles — deacons, priests and bishops — in direct descent, via the laying on of hands, from the original Apostles. By the way, “Episcopal” is an adjective: “I belong to the Episcopal Church.” The noun is “Episcopalian”: “I am an Episcopalian.”
Resources for exploration:
What is the Episcopal Church?